This question already has an answer here:

I am using QGIS2.4.0 on a Windows computer. When I export a map containing OSM landscape, the labels in the output map are smaller then in the view in the composer. (even if the view in the composer is at zoom 100%)

This is not the only difference, here an example (click to magnify images):

The view in the composer

view in the composer

The exported file

exported file

You can see that the labels are now impossible to read.

I want to be able to print and export the view as I see it in the composer.

I tried the solutions for the question How to improve OSM layer resolution in OpenLayers plugin while exporting? but that didn't help.

So the problem is not the openlayers plugin.

marked as duplicate by underdark qgis Jul 8 '17 at 18:03

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.